/Engine/Source/Runtime/Engine/Classes/PhysicsEngine/ClusterUnionComponent.h
The GT data is replicated from the server to the clients either via theFClusterUnionReplicatedDataon the cluster union component or per-child component data is replicated via theUClusterUnionReplicatedProxyComponent. Generally, the same flow is replicated on the client. The only exception is for replicating the X/R/V/W properties on the cluster union particle which does a GT -> PT data sync. There's no particula reason this happens...it just mirrors the single particle physics proxy here.
class UClusterUnionComponent : public [UPrimitiveComponent](API\Runtime\Engine\Components\UPrimitiveComponent)
FOnClusterUnion...
OnComponentAddedEvent
FOnClusterUnion...
OnComponentBoundsChangedEvent
FOnClusterUnion...
OnComponentRemovedEvent